Thermal transfer technology has been used for several decades to provide images, including color images, in receiving elements using infrared (thermal) laser devices. In general, most of these technologies rely on the conversion of infrared radiation to heat energy using an infrared radiation absorbing compound, and the subsequent transfer of one or more colorants from the exposed areas of a donor element to a receiving element. The images obtained in this manner can be monochrome or by a planned repetition of the process with various colorants in donor elements, a multi-colored image can be produced on a common receiving element. Such multi-color images can be used, for example, for generating color proofs or color filter arrays.
The basic thermal transfer technology is described for example in U.S. Pat. No. 5,126,760 (DeBoer) in which an IR absorbing compound is used to effect sublimation or diffusion of a colorant from a thermal transfer donor element to a receiving element.
U.S. Pat. No. 5,278,023 (Bills et al.) describes thermal transfer donor element containing a propellant layer to transfer colorants to receiving elements. In addition, U.S. Pat. No. 5,171,650 (Ellis et al.) describes a laser thermal donor element that is used to transfer a colorant to a receiving element using ablation imaging.
Other image forming thermal transfer donor elements are described in U.S. Pat. Nos. 5,578,824 (Koguchi et al.), 6,165,671 (Weidner et al.), 6,190,827 (Weidner), and 6,270,934 (Chang et al.). In particular, the Weidner patents describe thermal transfer donor elements having a hydrophilic layer, propellant layer, and colorant layer, arranged in that order on a substrate. The propellant layer usually includes an infrared radiation absorbing compound. They also describe the use of these donor elements to provide color images on receiving elements.
In known embodiments of thermal transfer donor elements, some of the infrared radiation absorbing compound transfer along with the colorants, thereby contaminating the color image on the receiving element and causing poor image quality. There is a need to provide improved thermal transfer donor element that provide improved transferred color images.